During the 2011 ICCA Finals at the Lincoln Center, Barden University's all-female a cappella group, the Barden Bellas, lose to their all-male rival group, the Barden Treblemakers, due to junior member Aubrey Posen's vomiting onstage in the middle of her solo. Four months later, aspiring DJ Beca Mitchell is a freshman at Barden University at the insistence of her father, a professor at the university, despite having no desire to attend college, instead spending her time making mash-up mixes of songs. She gets an internship at the school radio station, where she gets to know fellow freshman Jesse Swanson.
PLOT
At the university's activities fair, Beca is invited to join the Bellas by seniors and current co-leaders Aubrey and Chloe Beale, but she declines. Later, Chloe hears Beca singing in the shower, convincing her to audition. Although late for the audition, Chloe allows her to perform for them anyway. She auditions with a rendition of "Cups (When I'm Gone)", getting her into the Bellas along with the tough Cynthia Rose Adams, the flirtatious Stacie Conrad, the unusually quiet Lilly Onakuramara, the bubbly Jessica Smith, the alto Ashley Jones, the comedic Patricia "Fat Amy" Hobart, and the meek Denise. Meanwhile, Jesse joins the Treblemakers.
The Bellas participate in the 2012 ICCA Regionals, where, at Aubrey's insistence, they perform the same medley that helped the Bellas advance to the Finals the previous year. In spite of their stale setlist, the group manages to place second, sending them to the Semi-Finals. After the competition, the Bellas try to break up a fight between the Treblemakers and the Tonehangers, a male alumni a cappella group. Beca and Fat Amy accidentally smash a window with the Treblemakers' trophy, alerting police who then arrest Beca. Jesse contacts her dad to bail her out, causing a rift in her relationship with both. Aubrey insists on performing the same medley a third time, despite Beca urging them to be more daring. In the midst of their performance, Beca, hoping to reinvigorate the uninterested crowd, inserts an impromptu layering of "Bulletproof" into the set.
Aubrey angrily berates Beca for this and accuses her of hooking up with Jesse, a rule breach punishable by ejection from the Bellas. Jesse overhears and attempts to deny it, leading Beca to snap at them both and quit the Bellas. Despite the judges and crowd enjoying Beca's improvization, the Bellas do not advance to the Finals due to their third-place ranking behind the Treblemakers and the Footnotes. However, Jesse's roommate Benji Applebaum finds out that Footnotes leader Timothy is a high school student and reports it, disqualifying the Footnotes and allowing the Bellas to advance to the Finals. After spring break, Beca tries to reconcile with Jesse, but he rejects her, accusing her of pushing away everyone who cares about her.
During the Bellas' rehearsal, Chloe stands up against Aubrey, sparking a giant fight over the pitch pipe. Beca then returns, apologizes to the Bellas for changing the set without Aubrey's permission during the Semi-Finals, and asks to be given a second chance. After all of the Bellas have a heart-to-heart conversation, Beca rejoins the group, and Aubrey relinquishes her half of the leadership to Beca. Chloe discovers that after her spring break node removal surgery, she is able to sing bass notes. Meanwhile, Treblemakers leader Bumper Allen leaves the group after being offered a job as a back-up singer for John Mayer. With Bumper gone, Jesse persuades the Trebles to let Benji join the group in Bumper's place, a position Benji was denied earlier in spite of his impressive audition.
At the Finals, the Bellas perform a modern piece arranged by Beca, which includes "Don't You (Forget About Me)", featured in The Breakfast Club, one of Jesse's favorite movies. This acts as a more effective apology, and after the performance, she and Jesse kiss. Chloe's new ability to hit bass notes contributes to a fuller, more dynamic sound in the Bellas performance. The Bellas defeat the Treblemakers and win the national championship. Six months later, auditions for new members take place.
